Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
gm

Test String

Code Generator

Language

Generated Code

import Foundation let pattern = #"(?<timestamp>^.*?)\s(?<apic_host>.*?)\s%LOG_LOCAL(?<apic_facility_level>\d)-(?<apic_severity>\d)-SYSTEM_MSG\s\[(?<apic_code>.*?)\]\[(?<apic_lifecycle_state>.*?)\]\[(?<apic_rule>.*?)\]\[(?<apic_severity_text>.*?)\]\[(?<apic_DN_of_affected_MO>.*?)\]\s(?<apic_message>.*)$"# let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines) let testString = #""" 2023-02-27T13:55:00-06:00 apic-99 %LOG_LOCAL7-3-SYSTEM_MSG [F1298][raised][configuration-failed][minor][uni/epp/fv-[uni/TENANT/ap-APP/epg-Dealer-Server]/node-1105/polDelSt/fault-F1298] For tenant TENANT, application profile APP, deployment of application EPG Dealer-Server failed on node 1105. Reason Delivered,Node belongs to different POD 2023-02-27T13:55:00-06:00 apic-99 %LOG_LOCAL7-3-SYSTEM_MSG [F1298][raised][configuration-failed][minor][uni/epp/fv-[uni/TENANT/ap-APP/epg-Dealer-Server]/node-1105/polDelSt/fault-F1298] For tenant TENANT, application profile APP, deployment of application EPG Dealer-Server failed on node 1105. Reason Delivered,Node belongs to different POD 2023-02-27T13:55:03-06:00 apic-99 %LOG_LOCAL7-2-SYSTEM_MSG [F0321][soaking][unhealthy][critical][topology/pod-2/node-3/av/node-4/fault-F0321] Controller 4 is unhealthy because: Data Layer Partially Diverged 2023-02-27T13:55:03-06:00 apic-21 %LOG_LOCAL7-2-SYSTEM_MSG [F0321][soaking_clearing][unhealthy][critical][topology/pod-2/node-3/av/node-4/fault-F0321] Controller 4 is unhealthy because: Data Layer Partially Diverged """# let stringRange = NSRange(location: 0, length: testString.utf16.count) let matches = regex.matches(in: testString, range: stringRange) var result: [[String]] = [] for match in matches { var groups: [String] = [] for rangeIndex in 1 ..< match.numberOfRanges { let nsRange = match.range(at: rangeIndex) guard !NSEqualRanges(nsRange, NSMakeRange(NSNotFound, 0)) else { continue } let string = (testString as NSString).substring(with: nsRange) groups.append(string) } if !groups.isEmpty { result.append(groups) } } print(result)

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Swift 5.2, please visit: https://developer.apple.com/documentation/foundation/nsregularexpression